introduction to tswg & guide - version 1

I N T R O D U C T I O N T O T H E C R O S S I N D U S T R Y T R A C K S T I F F N E S S W O R K I N G G R O U P & G U I D E – V 2 1

CONTENTS

1. Importance of Track Stiffness

2. Cross Industry Track Stiffness Working

Group

3. The ‘Guide to Track Stiffness’

4. Further information

5. Future work

I N T R O D U C T I O N T O T H E

C R O S S I N D U S T R Y T R A C K S T I F F N E S S W O R K I N G G R O U P

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I N T R O D U C T I O N T O T H E C R O S S I N D U S T R Y T R A C K S T I F F N E S S W O R K I N G G R O U P & G U I D E - V 1 3

IMPORTANCE OF TRACK STIFFNESS

4

� ‘Track quality, continued track component performance and subsequent maintenance are highly

dependent upon the magnitude and variation of track stiffness’ (Hunt, 1993).

� ‘Track stiffness’ is the point load required to produce a unit deflection of the rail at the location

where the load is applied.

� A track that is too soft, or varies too widely over a short distance, may lead to excessive deformation

and a rapid loss of geometry.

� A track support that is too stiff may result in component damage.

� Track stiffness depends on the effective combined stiffnesses of all of the individual elements of the

track system combined (e.g. rail, pad, sleeper, ballast, formation).



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I N T R O D U C T I O N T O T H E C R O S S I N D U S T R Y T R A C K

S T I F F N E S S W O R K I N G G R O U P & G U I D E - V 1 5

Wet bed &poor drainage

Ballast attrition

Complex transitions

Hard spot

Broken fastening system

Soft trackbed

IMPORTANCE OF TRACK STIFFNESS

6

� Track component stiffness (e.g. rail, pad, sleeper) can be closely specified, however, formation

stiffness is usually more variable and less specified.

� Formation stiffness is influenced by soil type, geology, moisture content, compaction, structures,

transitions, etc.



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PAST CUTTING CONSTRUCTION

8

PAST EMBANKMENT CONSTRUCTION

EXAMPLES OF CURRENT NR BALLASTED TRACK DESIGN REQUIREMENTS

9

GC/RT5021 ‘Track System Requirements’

NR/L2/TRK/2102 ‘Design

& Construction of Track’

NR/L2/TRK/4239 ‘Track

Bed Investigation,

Design & Installation’

Current standards provide values for:

1. Formation stiffness for post renewal

and new track construction

2. Optimum dynamic sleeper support

stiffness (k) for existing track of

different speeds.

BACKGROUND

� The Track Stiffness Working Group is a Technical Advisory Group.

� It contains representation from parties with interest in track stiffness from across the industry.

� Formed in 2011 as an internal Network Rail Group of 9 members.

� Today is a Cross Industry Group of 40 members.



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ORGANISATIONS REPRESENTED

12I N T R O D U C T I O N T O T H E


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WHO IS INVOLVED?

13

Chair person:

� Andrew Buck

Members:

� Graham Barnard

� Yann Bezin

� Ian Bostock

� David Brooks

� Mat Brough

� Ian Coleman

� David Connolly

� Andy Cornish

� Brian Counter

� Gareth Evans

� Niall Fagan

� Andy Foan

� Andy Franklin

� Joao Pombo

� William Powrie

� Liam Purcell

� Paul Richards

� Phil Sharpe

� Graham Taylor

� Barnaby Temple

� Tom Tivey

� Alan Phear

� Mohamed Wehbi

� Brian Whitney

� Rob Whittle

� Peter Woodward

� Gurmel Ghataora

� Neil Gofton

� Mandela Govera

� Mick Hayward

� Geoff Hunt

� Paul Insley

� Dermot Kelly

� Andy Key

� John Lane

� Louis Le Pen

� Patric Mak

� Simon Morley

� Peter Musgrave

Expertise in Components, Trackbed, Formation, Drainage, Earthworks, Noise, Vibration,

Renewals, Maintenance, Measurement, Investigation, Modelling and Research



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BACKGROUND

14

Aims:

� Share best practice amongst participants.

� Solve current problem sites.

� Review current trials and research.

� Define future research and industry strategy.

Funding and Time:

� No funding.

� Engineers and organisations provide their time freely to

attend and participate.

� Meets 6 times per annum for half a day, which equates to

3 days per annum.



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KEY TOPICS

Design Principles :

� Transitions

� Track drainage

� Cast Crossings

� Embankment stability

� Earthworks

� Undersleeper pads

� Ballast mats

� Micro axial piling

� Ballast reinforcement

� Non ballasted track

� Asphalt track system

Measurement:

� Falling Weight Deflectometer

� Smart cameras

� Wireless void measurement

� Instrumented wheelset

Modelling:

� Vehicle dynamics

� Track

� Geotechnical

Projects:

� Track construction for Canal Tunnels

� Earthworks for Channel Tunnel Rail Link

� Earthworks for Swindon-Kemble

� Non ballasted track for Asfordby Tunnel

� High Speed Track Design for HS2

� Remodelling of London Bridge

� S&C refurbishment for East Midlands Route

Research:

� Vibration remediation techniques

� Ballast migration

� Fibre reinforcement of ballast

� Outputs from Innotrack

� Outputs from SustRail

Knowledge Sharing:

� Support to PWI ‘Managing Track Formation

Seminar’

� Support to PWI Geotechnics for Track Engineers

text book

� Support to UIC lateral resistance working group



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SUCCESSES TO DATE

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� Created a unique network of multi disciplinary

technical specialists in the field of track

stiffness.

� Raised awareness of the importance of track

stiffness and promoted good practice.

� Showcased new technology.

� Supported the development of the Rail Trackform

Stiffness Tester (see right).

� Supported PWI’s ‘Managing Track Formation

Seminar’.

� Supported PWI’s ‘Geotechnics for Track

Engineers’ text book.

� Undertaken a Knowledge Search summarising

existing industry research.

� Published the ‘Guide to Track Stiffness’.

Rail Trackform Stiffness Tester during design and development



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INTRODUCTION

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� The ‘Guide to Track Stiffness’ produced by the Cross Industry Track Stiffness Working Group is

intended to :

� help practising engineers to identify and understand faults associated with track stiffness

� select appropriate repair and remediation techniques to resolve the root cause.

� This presentation does not attempt to describe the contents of the Guide but instead is to introduce

it.

� The Guide includes:

� theory

� measuring techniques

� typical values

� case studies

� diagnosis advice.

� The Guide is freely available to all in electronic format.

� The Guide is owned, managed and updated by the Cross Industry Track Stiffness Working Group.



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FRONT COVER



EXTRACT FROM THE GUIDE




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GUIDE TO TRACK STIFFNESS

23

� The Guide is freely available to all in electronic format via:

1. RSSB’s SPARK knowledge sharing website.

� www.sparkrail.org

� Register or Login, then Search for ‘A Guide To Track Stiffness’.

2. The Permanent Way Institution’s Technical Hub website.

� https://www.thepwi.org/technical_hub/guides

� Look for ‘A Guide to Track Stiffness’.



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SUMMARY

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� ‘Track quality, continued track component performance and subsequent maintenance are highly

dependent upon the magnitude and variation of track stiffness’ (Hunt, 1993).

� The Cross Industry Track Stiffness Working Group is a network of multi disciplinary specialists with

the aim of advancing the discipline of track stiffness.

� The ‘Guide to Track Stiffness’ is intended to :

� help practising engineers to identify and understand faults associated with track stiffness

� select appropriate repair and remediation techniques to resolve the root cause.

� Further information is available from [email protected]



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POTENTIAL FUTURE WORK OF TRACK STIFFNESS WORKING GROUP

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� Support the development of:

� track remediation techniques, including the analysis of historical construction records and deterioration

rates to inform design

� pad and geo-synthetic specification and optimisation

� S&C, rail joint and transition design

� measurement technique standardisation, including application during renewal and new construction.

� Standard development.

� Share best practice, including additional case studies and publication of further Guides on:

� Lateral stiffness

� Non-ballasted track.

� Solve problem sites.

� Review trials and research.

� Help define future research and industry strategy.



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introduction to tswg & guide - version 1

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